[Ground-station] Please vote - Ambasat sensor

Sat Sep 28 15:56:18 PDT 2019

N8UR is not just a time-nut, he is in some senses THE time-nut.
Ultra-stable to you might mean it doesn't drift a kilohertz. To John, it
means he can fly one oscillator around the world, and then measure the
relativistic difference against one that stayed home. :-)

On Sat, Sep 28, 2019 at 1:16 PM John Ackermann. N8UR via Ground-Station
<ground-station at lists.openresearch.institute> wrote:

> Hi Douglas --
>
> OK, that makes sense as a neat experiment, but "ultra-stable" implies
> something a lot more complex and sent me off into the weeds.  I think the
> biggest challenge, as someone else pointed out, is that getting a
> transmitter authorized, even at very low power, probably creates a bunch of
> bureaucratic hurdles.
> On Sep 28, 2019, at 2:52 PM, Douglas Quagliana <dquagliana at gmail.com>
> wrote:
>>
>> Hi John,
>>
>> The idea was to have a very simple crystal oscillator (perhaps a very
>> small milliwatt class amplifier) and an antenna
>> such that the oscillator's signal (with Doppler) can be detected on
>> the ground.  No data, just a carrier that a
>> ground station with a simple antenna and perhaps a FunCube or RTLSDR
>> dongle can detect.
>>
>> The overriding principle is "keep it simple."  Generate just enough RF
>> output so that the oscillator's signal can be
>> detected on the ground -- and detection can be done at MUCH lower
>> signal levels than are needed to demodulate
>> a data signal. Ground stations know the frequency to listen at.  This
>> experiment would be placed on a short lived
>> LEO so that as the orbit decays and the spacecraft slowly spirals in
>> (over several months/years) the changing
>> orbit can be observed by watching the signal and it's Doppler
>> characteristics change over time.  It's not a very
>> interesting experiment at GEO where the orbit really never changes.
>>
>> The whole experiment (except the antenna) should fit on postage stamp
>> sized circuit board, weigh only a few
>> grams, and pull just a couple of milliamps.  The frequency could be
>> any frequency in any amateur band
>> authorized for satellite downlinks.
>>
>> I'm not sure what the specifications should be except that the
>> oscillator should be as stable as reasonably
>> possible within whatever the budget it, but if someone can help out
>> then let me know and we can
>> write the specification and propose it to be included as an experiment
>> on some future satellite.  The
>> experiment also needs a cool name.
>>
>> Perhaps we should move this to another thread...  if anyone is
>> interested, please let me know.
>>
>> 73,
>> Douglas KA2UPW/5
>>
>> On Fri, Sep 27, 2019 at 7:37 AM John Ackermann. N8UR <jra at febo.com> wrote:
>>
>>>
>>>  In this context, what does "Ultra Stable" mean?  There are a bunch of interesting challenges with crystals in space because of the launch shock, the huge temperature swings, and the thermal insulating properties of vacuum.
>>>
>>>  I know people who know about these things and would be glad to help if we wanted to do this, but a spec is the first requirement.  It would need to include (at a minimum) nominal frequency,  short-term stability,
>>>  phase noise, drift/aging, temperature response, and absolute frequency accuracy, along with mechanical things like shock rating, physical dimensions, and power budget.  There would have to be consideration
>>>  of thermal management as well, given the likely need for an oven.
>>>
>>>  (Note: I've never done spacecraft design, but I've picked up on these issues from conversations with those who have worked on space-borne USOs.)
>>>
>>>  73,
>>>  John
>>>  On Sep 27, 2019, at 1:32 AM, Michelle Thompson via Ground-Station <ground-station at lists.openresearch.institute> wrote:
>>>
>>>>
>>>>  We can design our own sensor. There's a blurb about it on the site and specs for the footprint and interface.
>>>>
>>>>  If someone commits to build and test, I can work with Ambasat to see if we can get it on there.
>>>>
>>>>  On Thu, Sep 26, 2019, 22:27 Douglas Quagliana < dquagliana at gmail.com> wrote:
>>>>
>>>>>
>>>>>  Rather than a sensor, could we get an ulta stable oscillator (USO) for some frequency in an amateur satellite band? We would just need the USO, a small amplifier and an antenna. Even an inefficient antenna. Even if we’re only radiating a few milliwatts. There’s still a lot of good science we can do from an unmodulated carrier with Doppler.
>>>>>
>>>>>  Regards,
>>>>>  Douglas
>>>>>
>>>>>  On Sep 26, 2019, at 6:24 PM, Michelle Thompson via Ground-Station < ground-station at lists.openresearch.institute> wrote:
>>>>>
>>>>>  There are solar panels.
>>>>>
>>>>>  From  https://ambasat.com/ambasat-2/ambasat-1/
>>>>>
>>>>>  "AmbaSats are just a little bigger than the size of a couple of postage stamps but have solar cells, a LoRaWAN radio transceiver..."
>>>>>
>>>>>  For the dashboard, there's a big hint here:
>>>>>  "Your AmbaSat-1 is fully TTN compliant so as well as viewing data in your Dashboard, you can sign-up for a TTN account and access your satellite’s sensor data directly using a range of different TTN extensions."
>>>>>
>>>>>  I think the dashboard is essentially The Things Network. I'll see what I can find out about the dashboard availability.
>>>>>
>>>>>  Interesting question about HABs! I think several people on this list are much more active than I am in designing and building payloads, and might be able to give an evaluation based on what's on the ambasat.com website.
>>>>>
>>>>>  -Michelle W5NYV
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>  On Thu, Sep 26, 2019 at 11:56 AM KC9SGV < kc9sgv at gmail.com> wrote:
>>>>>
>>>>>>
>>>>>>  The "three months in space" bit, makes me wonder.
>>>>>>  Maybe out of power by then ?
>>>>>>  (Don't see any solar panels on the board.)
>>>>>>  What would the possibility be to use the board as payload on a HAB (high altitude balloon).
>>>>>>  Maybe a Mylar balloon cluster achieving float, like the current Miami effort ?
>>>>>>  Then the environmental modules would make sense.
>>>>>>  Could you get the dashboard and web based tracking without buying the launch ?
>>>>>>
>>>>>>  Bernard,
>>>>>>  KC9SGV
>>>>>>  Sent from my iPad
>>>>>>
>>>>>>  On Sep 26, 2019, at 1:11 PM, Howie DeFelice via Ground-Station < ground-station at lists.openresearch.institute> wrote:
>>>>>>
>>>>>>  It has a LoRA radio on board which is really cool. I always thought that LoRA on a LEO would make a great Store  and Forward messaging sat. The chirp spread spectrum modulation handles doppler quite well and LoRA chips on carrier boards are easy to find to make ground stations.  Unfortunately there is little chance we could license it since the FCC decided that anything smaller than a 1U cubesat is too small to track.
>>>>>>
>>>>>>  Howie
>>>>>>  AB2S
>>>>>> ------------------------------
>>>>>>
>>>>>>  From: Ground-Station <ground-station-bounces at lists.openresearch.institute> on behalf of Michelle Thompson via Ground-Station <ground-station at lists.openresearch.institute>
>>>>>>  Sent: Thursday, September 26, 2019 11:26 AM
>>>>>>  To: Michelle Thompson via Ground-Station <ground-station at lists.openresearch.institute>
>>>>>>  Subject: [Ground-station] Please vote - Ambasat sensor
>>>>>>
>>>>>>  I bought into the Kickstarter for Ambasat.
>>>>>>  https://ambasat.com/
>>>>>>
>>>>>>  I’d like you all to help choose the sensor!
>>>>>>
>>>>>>  Choices here:
>>>>>>  https://ambasat.com/ambasat-2/sensor-options/
>>>>>>
>>>>>>  Disclaimer:
>>>>>>  This has nothing to do with our project. I acknowledge that Ambasat is controversial. No project funds are involved.
>>>>>>
>>>>>>  Why post this here?
>>>>>>
>>>>>>  Details:
>>>>>>  I asked Ambasat about a custom amateur radio payload, so we could test something for us. The kickstarter had that option. The lead of Ambasat said yes, amateur payload ok, several people I asked at Virginia Tech said go for it, and a small group looked at the specs and tried to design something useful for us. But, the very compact size and power budget was quite daunting. And the time frame was very short. We don’t have enough miniaturization or time. Instead of a custom board, we have a standard flight and a ground version.
>>>>>>
>>>>>>  Instead of quietly sending this up, I wanted to share it with the team as something fun. I just received the survey for the sensors, so we easily have a week at least to vote. It includes some sensors already. The free choice is an additional sensor slot.
>>>>>>
>>>>>>  -Michelle W5NYV
>>>>>>
>>>>>>
>>>>>>  --
>>>>>>  -Michelle W5NYV
>>>>>>
>>>>>>  "Potestatem obscuri lateris nescis."
>>>>>
>>>>>
>>>>>

-- 
Bruce Perens - Partner, OSS.Capital.
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